A general model for the surface tensions of deep eutectic solvents

Deep eutectic solvents (DESs) are a recently introduced class of sustainable solvents, being studied by many researchers in various fields. Because of the vast potential applications of DESs, it is necessary to have their physical properties available. Surface tension is an important physical property which has significant effects on permeability and bubbling, and hence in the design of processes. Up to date, there is no general model available in open literature for estimating the surface tension of DESs. In this study, for the first time, a general, simple, easy-to-use, and accurate correlation is proposed for the estimation of the surface tension of DESs at different temperatures. The correlation was developed based on a large data bank, including 553 data points, from 112 DESs having different natures. The model results were investigated by different statistical analyses and it was found that the correlation is not biased and shows normal behavior. The value of calculated overall AARD% of the model is 8.8%. The proposed model was compared to three general surface tension models in the literature and the comparison showed greater reliability and better agreement of the proposed model with respect to other literature models.